2007 Subaru Outback Owner's Manual - Page 349

Maintenance and service 11-13 In choosing an oil, you want the proper quality and viscosity, as well as one that will add to fuel economy. The following table lists the recommended viscosities and applicable temperatures. When adding oil, different brands may be used together as long as they are the same API classification and SAE viscosity as those recommended by SUBARU. & Recommended grade and viscosity under severe driving conditions If the vehicle is used in desert areas, in areas with very high temperatures, or used for heavy-duty applications such as towing a trailer, use of oil with the following grade and viscosities is recommended. API classification SM (or SL): SAE viscosity No.: 30, 40, 10W-50, 20W-40, 20W-50 Cooling system WARNING Never attempt to remove the radiator cap until the engine has been shut off and has cooled down completely. Since the coolant is under pressure, you may suffer serious burns from a spray of boiling hot coolant when the cap is removed. CAUTION . The cooling system has been filled at the factory with a high quality, corrosion-inhibiting, year-around coolant which provides protection against freezing down to −338F (−368C). For adding, use genuine SUBARU coolant or an equivalent: a mixture of 50% soft water (or clear and drinkable water) and 50% phosphate or non-amine type coolant. Use of improper coolants may result in corrosion in the cooling system. It is important to maintain protection against freezing and corrosion, even if freezing - CONTINUED - SAE viscosity number and applicable temperature *: 5W-30 is preferred. Engine oil viscosity (thickness) affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot weather, oil of higher viscosity is required to properly lubricate the engine.